It turns out that NGC 1365 hosts a rapidly spinning supermassive black hole at its center, and this black hole rotates very close to its theoretical limit imposed by Einstein's General Relativity.

Curiosity:

one usually refers to these black holes as "extremal" because their spin is close to its maximum value. In "God-given" natural units, the angular momentum of an extremal black hole is J=M^2.

Indeed, what is usually called the "Kerr limit" is J/M^2 = 1. This is by no means an "extremal" value!! [For example, Earth also spins around its axis and it has J/M^2~ 10^9 in natural units!]

This doesn't mean that these black monsters in the sky don't spin fast, quite the opposite: because their mass is HUGE, the angular momentum of an extremal black hole of about 10^6 solar masses [roughly the mass of the black hole at the center of the NGC 1365 galaxy] is as large as 10^13 times that of Earth... a pretty huge and fast spinning top!

PS:

The first author of the paper, Guido Risaliti is an Italian astrophysicists who works here at the Harvard-Smithsonian CfA and at Italian Institute for Astrophysics in Arcetri.